High-k dielectric materials are now used in many semiconductor devices as replacements for the silicon dioxide gate insulator that has previously been used. The high-k dielectric materials allow the continued scaling of semiconductor devices to smaller dimensions without sacrificing performance of the semiconductor devices. Polysilicon is a gate electrode material used in semiconductor devices which use silicon dioxide as the gate insulator. To manage the inherent threshold voltage value in the semiconductor devices that use high-k dielectric materials as the gate insulator, the polysilicon is replaced by an n-type or p-type metal. Barrier layers are used to prevent diffusion of the n-type or p-type metal toward the high-k dielectric materials as the diffusion may cause Time Dependent Dielectric Breakdown (TDDB) of the semiconductor devices. Thinner barriers that prevent diffusion of the n-type or p-type metal toward the high-k dielectric allow smaller, more reliable, more power efficient and faster semiconductor devices to be fabricated.